Selective relay



May 20, 1930. F. KESSELRING 1,759,792

I SELECTIVE RELAY Filed Dec. 15, 1926 y- Fig.5

Patented May 20, 1930 rnrrz xnssnrnme, or HERMSDORF,

MEYER A. G., or BERLIN,

NEAR BERLIN, GERMANY, ASSIGNOR TO DR. PAUL GERMANY, A JOINT-STOCK COMPANY SELECTIVE RELAY Application filed December 15, 1926, Serial No. 155,069, and in Austria August 6, 1926.

My invention relates to selective relays and more particularly to impedance relays the cutting-cut period of which increases in pro portion to the impedance of a system from a a defective point to the point where the nearest relay is situated. Relays of this type are superior to others in that they adapt themselves automatically to the conditions of the system.

It is an object of my invention to provide an improved impedance relay and to this end I provide three mechanically interconnected systems, to wit: an unretarded voltage system, a retarded current system including a thermal relay, and a system which is iniiuenced by the direction of the energy.

It is another object of my invention to provide in connection with the three systems aforesaid a cut-out switch which is not operated directly but is closed by hand and is locked in closed position by mechanism which is released by the cooperation of the three systems and in turn opens the switch.

Due to the fact that the voltage upon the occurrence of a short circuit in the network system decreases it is desirable that the Voltage system be very sensitive for comparatively low voltages. If the voltmeter included in the voltage system has a soft iron core, this may be effected by suitably shaping the core.

The current system is preferably composed of a lei-metallic strip through which the current flows, the current being preferably supplied through a small intermediate transformer. The arrangement of the transformer is such that from a predetermined value upwards the secondary current increases more slowly than. the primary current.

When a bi-metallic strip is employed for the current system a geometrically similar shaped strip may be employed for compensating the temperature. The strips may be pivoted so that they will bend at the same time, the compensating strip being held at one end and turning backwards the entire system, and this backward turning is made up for by the strip in which the current is flowing so that the strip is maintained in neutral position.

It is also possible to combine with the current system a curved eccentric the configuration of which permits the characteristic of the relay to be varied as desired.

In the drawings, relays embodying my invention are illustrated diagrammatically by way of example.

Fig. 1 is a diagram showing the three systems, the switch and its switching bar,

Figs. 2, 3, and 1 illustrate various types of switching bars,

Fig. 5 illustrates a compensation device.

Referring now to Fig. 1, a is the voltage system comprising a coil 1, its core 2 and a cam 3 which is adapted to be displaced along a slide bar 4. Z) is the retarded thermal current system comprising a heated wire 5 on a roller 6, an eccentric 7 on the axis of the roller 6, and a spring 8 attached to the wire 5 and tending to turn the eccentric 7 counter-clockwise when. the wire 5 is heated. 0 is the energy-directed relay which is here shown as a Ferrari relay comprising a voltage coil 9, 9, a current coil 10, and a plate 11.

c a switch comprising a spring 16 which tends to close the contact, 14 is a pawl in the shape of a bell-crank lever fulcrumed at 15 which when engaging the lower arm of the switch 0 prevents the spring 16 from closing it, and 13 is a pawl, also in the shape of a bellcrank lever 12, 13, which is connected with the directional relay 0 and under certain con ditions, as will be described, holds the pawl 14 in its locking position. cl is the triangular switching bar.

There are connected to the bus bars A, the voltage transformer B and the oil-break. switch X with the releasing coil D, also the current transformer F to the conducting wire E and the neighboring station. This current transformer F feeds firstly the winding around the core 10 and secondly the heating wire 5. The voltage coil 1 and the outer coil are connected to the voltage transformer.

it will be understood that Fig. 1 shows the important parts of my relay, (1 and b representing respectively the voltage and current members and c the directional relay which allows the relays a and b to operate only when bi-metallic temperature of the switch 6 by throwing out the ing the pawl 13,

energy is flowing from a switching station, being the switch, and all its switching bar.

When an overload occurs in the system the voltage will generally be reduced and the position of the cam 3 will be varied accordingly. The heated wire 5 will become hotter under the influence of the increased current and will consequently expand, allowing its spring 8 to turn the eccentric 7 counter-clockwise through the medium of its roller 6. The eccentric is in contact with the pivot 19 of the triangular switching bar (Z and pushes the bar to the left until its pivot 17 is arrested by the cam 23. Upon further rotation the hypotenuse of the triangle will be shortened against the action of a spring 24 as will be described with reference to F 2 and this causes the pivot 18 at the apex of the triangle to move upwards and to release the lower arm pawl 14 if it has been released by the pawl 13 which, as mentioned, will only occur if energy flows from the station. The contact or switch 6 will now be closedby its spring 16.

On the other hand, it ener v is flowing into the switching station wherein the relay is built the pawl M is retained by the pawl 13 so that the spring 24 is further compressed but the switch c cannot be closed.

If there short circuiting at K only the switch may be released, because the energy flows over from the station, the Ferraris plate 11 must rotate clockwise so that by liftthe locking member is of the contact 0 is released.

Referring now to Fig. 2, the switching bar is composed of three rods 21, 22, am 23 which are connected at 17, 18, and 1Q. The rod 23 is divided at the centre and a spring 2st is inserted between them. are guides for the two parts of the rod. The eccentric 7 acts in the direction of the arrow 25 and displaces the switching bar horizontally until its pivot abuts at the cam 3. As soon as this occurs the triangle will be deformed by the shortening of its hypotenuse 23, compressing the spring 24 and raising the pivot 18 at the apex as indicated by the arrow. This motion of the a pen throws out the pawl 14 as described, if it has been released by the pawl 13. 7

Referring now to Fig. 3, the triangular switching bar (Z is replaced by a double-armed lever 31 which is tulcruined at 32 to the shank of a pawl 33 adapted to slide in a guide 34. Tlie end 36 of tr e lever is acted on by the eccentric 7 of the current system Z) and its other end 37 is adapted to abut against the cam 23 of the voltage system c.

lVhen the eccentric 7 is rotated the lever 31 will turn. on its fulcrum 32 until its end 37 is arrested by the cam 3. Now, the two-armed lever changes into'a one-armed lever which is fulcrumed at 3 and upon further rotation of the eccentric 7 the pawl 33 is withdrawn circuit with from the arm of the switch 6 so that the spring 16 is freeto close the switch.

The device illustrated in Fig. 4 is similar to the one described but its pawl is fulcrumed at 442 and the pivot 32 about which the lever 31 is rocking before being arrested by the cam 3, is secured to the shank 43 of the cam.

Referring now to Fig. 5, 51 is the bi-metallic strip in which the current is flowing and 52 is the com ensation strip which is held a 55, the two strips pivotally carried at 53. l Vhen the ambient temperature increases the strip 52 will bend upwards and, as the strip is held at 55 the system will rock bodily about its pivot 53 in counter-clockwise direction. The strip 51 which is geometrically similar to the strip 52, will also bend as shown, i. e., in opposite direction to that of the strip The backward rotation by the strip 52 is therefore made up for by the opposite deformation of the strip 51 so that the upper end of this strip will remain in position notwithstanding the change of temperature.

The means for operatively connecting the two strips may be varied, the only important condition being that the two strips should be geometrically similar and so arranged that their deformations willbalance each other.

I claim:

1. A protective device for an electrical net work system comprising avoltage relay, a directional relay having voltage and current coils, a thermal relay included in the circuit of said current coil, each of said relays being connected to said system, electrical means for opening said system, a switch in circuit with said means for controlling the operation thereof, means operated by said voltage relay and said thermal relay for actuating said switch, and means operated by the directional relay for controlling the closing of said switch.

2. A protective device for an electrical net work system. comprising a voltage relay, directional relay iaving voltage and current coils, each of said relays being connected to said system, a thermal relay included in the circuit of said current coil, electrical means for opening with'said means for controlling the operation thereof, a cam actuated by said voltage relay, a second cam actuated by said thermal relay, means, operable by said cams for actuating said switch, and means operated by the directional relay for controlling the clos ing of said switch;

3. A protective device for an electrical net work system comprising a voltage relay, a

directional relay, having voltage and current coils, both of said coilsbeing connected to said systenna thermal relay included in the circuit of said current coil, electrical means for opening said system, a switch in said electrical means for consaid system, a switch in circuit trolling; the operation thereof, a cam actuated by voltage relay, a second rain actuated by said thermal relay, a switch bar operable by said cams for actuating said switch, ron'iprisii a trian ular s stem of 5 r n circuit with said electrical means or con trolling the Operation thereoi, a cam actuatcr. said voltage rela a second cam aet iated by said lierma 1, 1y, pawl means for normally niaint ring; said switch in open position, a to le mechanism actuated by said cams for t easing said means maintaining said switch in normal open position, and means op rable by the directional relay and associated with said pawl for controlling the closing 01" said. switch.

5. A protective device fo' an electrical net WOIk system comprising a voltage relay, a

directional relay having voltage and current coils, a voltage transformer connecting said voltage coil to said electrical system, a

current transformer characterized by the act that its seconda current increases more slowly than its primary current connecting aid current coil to said system, a thermal re- 1!" included in the ircuit 01'' said. current ii, each of said relays being connected to 40 s id systen'i, electrical moans toropering said system, a switch in. circuit with said means for controlling the operation thereof, means operated by said voltage relay and said thermal relay tor actuamng said switch, and

means operated by the directional relay for controlliir the cirsinp; of said switcl (iv A protective device for an electrical not tori; 2cm *omprising voltages, relay, a directional relay having w micand current coils, a i i in the cirmal relay ia.-

cult oi" salt: each oi said relays being cormectcd to said system, a tempera ture compeu tin device in the thermal relay circuit. rica l me. "or opening :-:ystem, a s i in circi means for coutrolli operation thereof, means operated hy eJlCt voltage in ay and said thermal relay "for actuating said switch, and meal s opera d by the di 'ectioiial relay for 6. controlling the closing of said switch.

in testimony whereof, I have signed my name to this specification.

FRITZ KESSELRING, 

